Make sure to use the right php binary

In order to use the same binary that was used to
execute Composer the PHP_BINARY constant is used.

Author: sebastianfeldmann

src/ComposerPlugin.php

@@ -218,7 +218,9 @@ private function runCaptainCommand(string $command): void
         }
 
         // sub process settings
-        $cmd   = $executable . ' ' . $command . $ansi . $interaction . $forceOrSkip . $configuration . $repository;
+        $cmd   = PHP_BINARY . ' '  . $executable . ' ' . $command
+               . $ansi . $interaction . $forceOrSkip
+               . $configuration . $repository;
         $pipes = [];
         $spec  = [
             0 => ['file', 'php://stdin', 'r'],